Studies of symptoms in primary care

Several series of articles dealing with the critical appraisal of the medical literature1–3 have been published. While studies of treatments, side effects, causation, prognosis, diagnostic tests and overviews/meta-analyses have been discussed thoroughly, there is a particular type of study that has not received sufficient attention in the past, i.e. studies examining patients presenting with a defined symptom in health care settings. In particular, the questions that these studies aim to answer are